Johnson grew up in Freeport, Ill., as the 9th of 10 children. He majored in history at the University of Illinois (B.A., 1968) and, after studying public affairs at Princeton University (M.A., 1972), moved to Washington, D.C., where he worked for the Corporation for Public Broadcasting and the National Urban League. He began cultivating valuable political and business connections that later helped him bankroll his vision of creating a black-owned cable television company. As a lobbyist for the nascent cable industry from 1976 to 1979, he noticed that the large African American TV audience was going unrecognized and untapped. Johnson built BET from a tiny cable outlet, airing only two hours of programming a week in 1980, to a broadcasting giant that claimed an audience of more than 70 million households.

In 1991 BET became the first black-controlled company to be listed on the New York Stock Exchange. BET thrived in the 1990s, adding more cable channels and expanding its reach through new film and publishing divisions, music channels, and a Web site. Viewership expanded along with the product line, while major media companies began to invest in the growing network. After taking BET private again in 1998, Johnson and his partners sold BET Holdings to the giant media group Viacom in 2001 for some $3 billion, though he remained at BET as its chief executive officer until 2005. The sale made him the first African American billionaire. Johnson then formed the umbrella group RLJ Companies, which operated widely in the media, sports, gaming, real estate, and hospitality industries.

After attempting to purchase a National Basketball Association franchise throughout the 1990s, Johnson was approved as the owner of an expansion team in Charlotte, N.C., in 2003 (the city’s former team, the Hornets, had just moved to New Orleans, La.). The new team, called the Bobcats, began competition in 2004. Johnson’s purchase of the franchise, estimated at $300 million, also included the Sting, the Women’s National Basketball Association team in Charlotte. Johnson launched C-SET (Carolinas Sports Entertainment Network), a regional sports and entertainment cable TV network, in October 2004. In 2006 Johnson, along with the film producers Harvey Weinstein and Bob Weinstein, created the company Our Stories Films to develop family-oriented movies aimed at African American audiences. In 2007 RLJ Companies, international development and humanitarian aid organization CHF International, and the U.S. Overseas Private Investment Corporation—an independent government agency created in 1971 to aid overseas investments and promote economic development in newly emerging markets—established the Liberian Enterprise Development Finance Company to promote investment and project development in Liberia.